報告書番号

N10040

タイトル（和文）

蛍光染料を含む地下水の水質評価における前処理法の提案－ボーリング調査およびトレーサー試験におけるイオン濃度や同位体比の正確な評価のために－

タイトル（英文）

Removal method of fluorescent dyes as pretreatment for measurement of major ion concentrations and hydrogen and oxygen isotopic ratios

概要 （図表や脚注は「報告書全文」に掲載しております）

ボーリングの掘削水の指標として、あるいは地下水移動の指標として、しばしば用いられる蛍光染料が混入したサンプルでは、蛍光染料の影響によって正確なイオン濃度や水素・酸素同位体比測定が阻害されるだけでなく、装置の不良動作等の原因になるなどの影響が懸念される。本研究では、代表的な4種の蛍光染料（ウラニン、エオシン、ナフチオン酸ナトリウム、アミノＧ）を除去し、イオン濃度や同位体比評価を可能な手法について検討した。ウラニンとエオシンは合成吸着樹脂に対する疎水的な吸着を用いて、ナフチオン酸ナトリウムとアミノGは陰イオン交換樹脂を用いてそれぞれ除去可能であることを示した。合成吸着樹脂を用いる方法はイオン濃度や同位体比に影響がほとんどなく、陰イオン交換樹脂は陽イオンと同位体比への影響がほとんどないため、蛍光染料を含むサンプルに対する上記項目評価の前処理として活用することが可能である。

概要 （英文）

The major ion concentration and isotope ratio of hydrogen and oxygen can provide important information for migration of groundwater. Sometimes, quantitative estimation of these chemical and isotopic characteristics of solution is necessary for groundwater containing fluorescent dyes, which are used in drilling borehole and tracer experiments. However, sometimes correct estimation is disturbed by dyes and they become a cause of troubles for measurement equipments. Thus development of method to remove dyes is required so that the characteristics of groundwater can be estimated without the negative effect of dyes on measurement or equipments.
In this study, removal of four representative dyes (Uranin, Eosin, Naphthalenesulfonic acid sodium(NAP) and Amino G acid potassium salt (AG)) was investigated. Uranin and Eosin were found to be removed by non-ionic synthetic resin: HP2MG. 99.99% of the dyes were removed from initial solutions containing dyes with 10 mg/L after contact with resin, while the contact had little effect on ion concentrations and oxygen and hydrogen isotope ratios. Thus the chemical and isotopic characteristics of groundwater samples containing Uranin and Eosin can be obtained by using the HP2MG resin. On the other hand, the NAP and AG were found to be difficult to remove by the HP2MG resin but they were able to be removed by anion exchange resin (Dowex1x8). Though contact of solution with Dowex1x8 did not affect cation concentrations and hydrogen and oxygen isotope ratios, anion concentrations were changed by the contact. Therefore the Dowex1x8 is only applicable to estimation of the cation concentrations and isotope ratio of hydrogen and oxygen. When both anion and cation concentrations from the samples were necessary, Uranin or Eosin were recommended as a tracer in drilling or tracer experiments.

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